The Automatic Dependent Surveillance-Broadcast (ADS-B) services and protocols are used for tracking the position, heading, and speed of aircraft. In upcoming years, the United States will require that a majority of aircraft operating within its airspace be equipped with some form of an ADS-B transmitter. Currently, aircraft use antennas on the top and bottom of the aircraft to communicate with other aircraft and ground networks to share their location, speed, and heading. These current communications are generally aircraft-to-aircraft and aircraft-to-ground communications. However, the aircraft-to-ground communications are subject to multiple limitations. For example, common ground equipment can interfere with transmitted signals, mountains and tall buildings can obstruct signals from low altitude aircraft, the range of ground terminals does not extend to oceanic flights, and the density of ground terminals may affect coverage. Further, coverage provided by ground equipment is proportional to the density of ground terminals.
To assist the limitations of aircraft-to-ground communications and provide oceanic coverage, others have proposed installing ADS-B receivers on satellites. For example, IRIDIUM has sent a request for information regarding augmenting its low earth orbit satellites with ADS-B receivers to extend the terrestrial ADS-B infrastructure to provide continuous global coverage. However, current aircraft have preinstalled low gain antennas and transmitter systems with a fixed transmission power. The low gain and low transmission power inhibit the communication of aircraft position reports over the large distance separating aircraft and satellites.